Tuning NMC Structure via Calcination: Insights from Powder X‐Ray Diffraction

The electrochemical performance of LiNi x Mn y Co z O 2 (NMC) materials depends strongly on their composition and structure. This study investigates the influence of calcination temperature on the structural, morphological, and electrochemical properties of various NMC materials. For the first time, a conventional powder X‐ray diffractometer is used for in situ analysis of NMC calcination, revealing a four‐stage transition from precursor to hexagonal structure and composition‐dependent transition temperatures. This accessible method offers advantages over synchrotron‐based techniques. In situ X‐ray diffraction (XRD) enables selection of annealing temperatures for ex situ studies, which are correlated with electrochemical behavior using scanning electron microscopy, XRD, and chronopotentiometry. Raman mapping, which has not previously been applied in this manner, provides novel insight into the local structure and stability of the material. Additionally, the role of calcination atmosphere in Ni‐rich NMCs is examined. The results guide further development of advanced NMCs, including core–shell materials, and demonstrate the practicality of laboratory‐based structural methods for broader materials research.